This paper explains the major features and development results of the R350C rotary diesel engine series recently developed by Combat Propulsion Systems division of L-3 Technologies. This new rotary diesel engine series has been engineered specifically to operate on military grade fuels (JP-8/F24) and perform in power dense military applications, including auxiliary power units, hybrid propulsion and lightweight primary propulsion for combat vehicles. The rotary design allows for single, dual and triple rotor engine configurations with increasing power and power density ratings with each added rotor.